The present invention is concerned with a diagnostic test carrier with at least two layers which are fixed at a distance from one another so that there is a gap present between them and is also concerned with a process for the production of such a test carrier.
For the qualitative or quantitative analytical determination of components in body fluids, especially in blood, so-called carrier-bound tests have recently been used to an increasing extent. In these, reagents are embedded into appropriate layers of a solid carrier which is brought into contact with the sample. The reaction of the sample and reagents results in a detectable signal, especially a color change, which can be evaluated visually or with the help of an apparatus, usually by reflection photometry.
Test carriers are frequently constructed as test strips which consist essentially of a longitudinal support layer of synthetic resin material with test fields applied thereon. However, test carriers are also known which are made as square or rectangular platelets.
Test carriers of the initially described kind are known, for example, from Research Disclosure, Vol. 200, Abstract No. 22, pp. 554-557/1980 (in the following referred to as RD). The layers are there referred to as support member and as cover member. Both parts are planar sheets made of a solid synthetic resin material. For the production of a gap between the parts, a liquid-impermeable intermediate disc is placed on their circumference. The parts are connected, for example, by conventional adhesives or by ultrasonic welding.
A similar test carrier construction is described in U.S. Pat. No. 4,426,451.
From Federal Republic of Germany Patent Specification No. 26 41 097 and from U.S. Pat. No. 4,088,448, there is known a test carrier-shaped cuvette in which a gap is present within a one-piece synthetic resin part.
In all these cases, the gap serves for the transport of a liquid in the gap with the help of capillary force. In the case of the construction of diagnostic test carriers, this is frequently a useful constructional element. Thus, for example, the gap, as described in the RD reference, serves to fill a certain hollow space of the test carrier with a sample liquid. The flow of liquid can, as described in RD, possibly also be interrupted and, on the basis of a pressure impact, again be continued.
In spite of these advantages, the gap construction for test carriers has not been used hitherto to any great extent, the reason for which may well be that the previously known test carriers of this kind are laborious to produce.